This relates generally to imaging devices, and more particularly, to signal line voltage settling in imaging devices.
Image sensors are commonly used in electronic devices such as cellular telephones, cameras, and computers to capture images. In a typical arrangement, an electronic device is provided with an array of image pixels arranged in pixel rows and pixel columns. The image pixels contain a photodiode for generating charge in response to light (e.g., by photoelectric conversion). Circuitry is commonly coupled to each pixel column for reading out image signals from the image pixels using a corresponding column line.
In general, the column line voltage needs to settle to either a signal voltage or a reset voltage before sampling of the column line should occur. However, there is usually a long delay to do so as the drive strength of a corresponding pixel source follower transistor is limited. Because sampling an unsettled voltage on the column line will result in image artifacts, to avoid the image artifacts, image sensor operations will be significantly delayed.
It would therefore be desirable to provide imaging systems with improved column line voltage settling.